While my prior U.S. Pat. No. 3,949,745 dated Apr. 13, 1976 and U.S. Pat. No. 4,099,527 dated July 11, 1978 disclose and claim novel floating siphon-type regulators for incorporation in parenteral fluid administration sets which were earlier evaluated by persons qualified to judge same to represent an advance in the art, such have not been accorded commercial status, due to alleged complexity in their respective start-up procedures; because of their alleged ability to provide a constant flow rate in but a limited range of application; and/or further because they failed to take into account the fact that solution viscosity differences which reflect themselves in the differing weights of the various solutions being used can affect the absolute rate of flow and hence of delivery of the fluid to the needle.